Find every subdomain
of a domain.

Every hostname under a domain that ever appeared in a public TLS certificate — with certificate counts, first/last seen and live DNS status.

4 hosts · 229 ms

HostCertsFirst seenLast seenDNS
cloud.otr.otrsolutions.com 2 2026-04-19 2026-09-20 servfail
image.otr.otrsolutions.com 3 2026-05-05 2026-06-13 ok
click.otr.otrsolutions.com 1 2026-05-02 2026-05-02 ok
view.otr.otrsolutions.com 2 2026-05-02 2026-10-03 ok

Programmatic access, with DNS A records: API GET /v1/hosts/otr.otrsolutions.com (API key for paging).

Shown here: hostnames with a certificate that is valid now or expired within the last 90 days. The full history since 2013 — hostnames whose last certificate expired earlier — is a Pro plan method: GET /v1/hosts-history/otr.otrsolutions.com.